I brewed a nano batch of single grain IPA and I don't know what I have done wrong.

Before I started, I calculated the O.G. and F.G. as shown in the picture bellow. After boiling the wort from 5.3 liters to 4.4 liters (~1 hour), I measured the O.G., and found it only to be 1.074 (pre-boil was 1.065).

The beer is in a small carboy now, so I haven't measured the F.G. yet.

Brewing process:

  1. Heated up 4.4 liter of water to 72° Celsius (~161° Fahrenheit)
  2. Added crushed grains, the temp is now around 67° Celsius (~152° Fahrenheit)
  3. Turned off the stove and waited for an hour, but kept the temperature over 65° Celsius (~149° Fahrenheit)
  4. Started lautering with a sieve and washed the grains with warm water(around 67° Celsius), ended up with 5.3 liters of wort
  5. Started boiling the wort. After it reached boiling point, I turn down the heat the stove
  6. Still boiling a little bit for an hour while I added some hops. After the hour I got 4.4 liters of wort left. Measured the O.G. at 1.074. (used this calculator to get the right O.G. from hot wort)
  7. Cooled the wort down and racked it to the carboy & added yeast

Is there anything I'm doing wrong?

Are there some common causes for not achieving an expected O.G.?

enter image description here

  • Can you walk us through your mashing and lautering process? Did you crush the grains? How much water did you use to mash? Did you batch sparge, fly sparge, or no sparge? How much water did you sparge with?
    – Scott
    Feb 11, 2014 at 18:42
  • Measuring gravity at room temp is important, if not, then you need to correct since the gravity changes with temperature.
    – mdma
    Feb 11, 2014 at 19:41

2 Answers 2


The key piece that's missing here is extraction efficiency - how much sugar you can get out of the grains.

In the calculator, it's set at 80%, but it's doubtful you got that just from steeping and lautering in a pot. You typically need continual recirculation to get 80%+. With my old equipment (a large cooler with a hand-made series of pipes with slits.) I used to average 70%.

So, my guess is you did nothing wrong, other than you don't know the efficiency of your brewing system yet. Now you know the actual preboil OG you got, you can use that to work out your typical efficiency.

Your actual efficiency is

65 / 96 * 0.80 = 54%

This is typical for steeping small batches since a lot of the grain doesn't come into contact with much water, especially during sparging. Next time, just put in 55% into the calculator and your OG will come out more in line with what is planned.

Efficiency is a complex topic - for tips on finding out where you are losing efficiency see Troubleshooting Brewhouse Efficiency, and focus on the mash extraction and lautering sections.

  • Thanks, it all make sense now. I tried putting 52 % efficiency in the calculator and its almost spot on!
    – Bjorn
    Feb 11, 2014 at 20:30
  • That kind of begs the question doesn't it, to calculate your actual poor efficiency, and then say that if you had just plugged that number into your calculator, your efficiency would not be so poor relative to expectations? I also don't know where the idea of low grain-water contact comes from - that depends on mash thickness, right? I do a lot of mini-mashing, and consistently get 66% brewhouse efficiency (into the fermenter) with a large mill gap and poorly-performing mash tun. I agree that the OP should be focused on is getting a consistent brewhouse efficiency. Feb 12, 2014 at 1:21

Besides the potential causes that @mdma cites (possibly mash is too thick, leading to poor contact of water with grain and poor sparging), which can be solved by having a more liquid mash (at least 0.55L of strike water per kg of grain, or 1.3 qts. per lb.), a primary cause is the fact that your efficiency tends to decline as your grain volume (OG) increases.

  • yes, very true - higher OG batches tend to have less efficiency due to more sugars remaining in the grains, unless you make 2 brews partigyle, or increase pre boil volume and boil time.
    – mdma
    Feb 12, 2014 at 9:41

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